I'm using Windows 10 and today I accidentally hit the key combination: Ctrl+Shift+Win+B.
As a result, the screens went black for about a second and I heard a beep.
This is reproduceable; every time I hit the aforementioned key combination, the same behavior occurs.
Searching on the web I could find nothing about this except a reddit thread in which a user said he observed a similar behavior in Windows 8 by pressing Ctrl+Win+B (no Shift).
So, what is this key combination used for?